PyVista error trying to cast a shadow onto a gridded plane - vtk

Question

PyVista is great, and let's me do lots of cool things very conveniently. I would like to cast the shadow of a 3D object onto a plane with grid lines. Here's what I would like, minus the shadows, shadows=False, gridlines=True
I can enable shadows without the grid lines: gridlines=False, shadows=True
but when I try to do both gridlines=True, shadows=True I get a massive error trace as per below and a result just like above, shadows but no grid lines.
QUESTION: is what I am trying to possible? Am I misunderstanding grids and shadows, have I coded it wrong, or is this a bug. My bigger program, with more graphical entities will segfault. I am running PyVista 0.29.0, Python 3.8.5 on MacOS 10.15.7. Similar problems arise if I try to cast the shadow on to a StructuredGrid.
Below is my minimal code example
import pyvista as pv
import vtk
import numpy as np
# change these values
gridlines = True
shadows = False
plotter = pv.Plotter(polygon_smoothing=True, window_size=(2000,2000))
plotter.disable_parallel_projection()
sphere = pv.Sphere(radius=0.3, center=(0,0,1))
plotter.add_mesh(sphere, ambient=0.2, diffuse=0.5, specular=0.8, specular_power=30,
smooth_shading=True, color='dodgerblue')
# add the grid
grid = pv.Plane(i_size=5, j_size=5)
plotter.add_mesh(grid, show_edges=gridlines, ambient=0, diffuse=0.5, specular=0.8, color='red', edge_color='white')
if shadows:
# do the shadows
shadows = vtk.vtkShadowMapPass()
seq = vtk.vtkSequencePass()
passes = vtk.vtkRenderPassCollection()
passes.AddItem(shadows.GetShadowMapBakerPass())
passes.AddItem(shadows)
seq.SetPasses(passes)
# Tell the renderer to use our render pass pipeline
cameraP = vtk.vtkCameraPass()
cameraP.SetDelegatePass(seq)
plotter.renderer.SetPass(cameraP)
plotter.set_background('white')
plotter.show()
Error trace:
(dev) [233 ~...code/RVC3-python/tools] % /Users/corkep/opt/miniconda3/envs/dev/bin/python /Users/corkep/Dropbox/code/RVC3-python/chapter8/pvbug.py
2021-03-11 19:57:38.908 ( 0.621s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b5f90): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:38.908 ( 0.622s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b6840): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:38.908 ( 0.622s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b7120): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:38.908 ( 0.622s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b7a00): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:38.908 ( 0.622s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b82e0): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:38.990 ( 0.704s) [ 84DF2C] vtkShaderProgram.cxx:452 ERR| vtkShaderProgram (0x7fee29ba49b0): 1: #version 150
2: #ifdef GL_ES
3: #ifdef GL_FRAGMENT_PRECISION_HIGH
4: precision highp float;
5: precision highp sampler2D;
6: precision highp sampler3D;
7: #else
8: precision mediump float;
9: precision mediump sampler2D;
10: precision mediump sampler3D;
11: #endif
12: #define texelFetchBuffer texelFetch
13: #define texture1D texture
14: #define texture2D texture
15: #define texture3D texture
16: #else // GL_ES
17: #define highp
18: #define mediump
19: #define lowp
20: #if __VERSION__ == 150
21: #define texelFetchBuffer texelFetch
22: #define texture1D texture
23: #define texture2D texture
24: #define texture3D texture
25: #endif
26: #endif // GL_ES
27: #define varying in
28:
29:
30: /*=========================================================================
31:
32: Program: Visualization Toolkit
33: Module: vtkPolyDataFS.glsl
34:
35: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
36: All rights reserved.
37: See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
38:
39: This software is distributed WITHOUT ANY WARRANTY; without even
40: the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
41: PURPOSE. See the above copyright notice for more information.
42:
43: =========================================================================*/
44: // Template for the polydata mappers fragment shader
45:
46: uniform int PrimitiveIDOffset;
47:
48:
49:
50: // VC position of this fragment
51: //VTK::PositionVC::Dec
52:
53: // Camera prop
54: uniform int cameraParallel;
55:
56:
57: // optional color passed in from the vertex shader, vertexColor
58: uniform float ambientIntensity; // the material ambient
59: uniform float diffuseIntensity; // the material diffuse
60: uniform float opacityUniform; // the fragment opacity
61: uniform vec3 ambientColorUniform; // ambient color
62: uniform vec3 diffuseColorUniform; // diffuse color
63:
64:
65: // optional surface normal declaration
66: //VTK::Normal::Dec
67:
68: // extra lighting parameters
69: uniform vec3 lightColor0;
70: uniform vec3 lightDirectionVC0; // normalized
71: uniform vec3 lightColor1;
72: uniform vec3 lightDirectionVC1; // normalized
73: uniform vec3 lightColor2;
74: uniform vec3 lightDirectionVC2; // normalized
75: uniform vec3 lightColor3;
76: uniform vec3 lightDirectionVC3; // normalized
77: uniform vec3 lightColor4;
78: uniform vec3 lightDirectionVC4; // normalized
79:
80: uniform float depthC;
81: vec2 calcShadow(in vec4 vert,
82: in sampler2D shadowMap,
83: in mat4 shadowTransform,
84: in float attenuation,
85: in int shadowParallel,
86: in float sNearZ, in float sFarZ)
87: {
88: vec4 shadowCoord = shadowTransform*vert;
89: float expFactor = 8.0;
90: float thickness = 0.0;
91: if(shadowCoord.w > 0.0)
92: {
93: vec2 projected = shadowCoord.xy/shadowCoord.w;
94: if(projected.x >= 0.0 && projected.x <= 1.0
95: && projected.y >= 0.0 && projected.y <= 1.0)
96: {
97: float ldepth = shadowCoord.z;
98: if (shadowParallel == 0) { ldepth = (shadowCoord.w - sNearZ)/(sFarZ - sNearZ); }
99: float depthCExpActual = exp(- depthC*ldepth);
100: float depthCExpBlured = texture2D(shadowMap,projected).r;
101: expFactor = depthCExpBlured * depthCExpActual;
102: float depth = log(depthCExpBlured)/depthC;
103: thickness = clamp(ldepth - depth, 0.0, 1.0)*(sFarZ - sNearZ);
104: if (expFactor > 1.0) { expFactor = 1.0; }
105: }
106: }
107: return vec2(1.0 - attenuation + attenuation*expFactor, thickness);
108: }
109: uniform int shadowParallel0;
110: uniform float shadowNearZ0;
111: uniform float shadowFarZ0;
112: uniform float shadowAttenuation0;
113: uniform sampler2D shadowMap0;
114: uniform mat4 shadowTransform0;
115: uniform int shadowParallel1;
116: uniform float shadowNearZ1;
117: uniform float shadowFarZ1;
118: uniform float shadowAttenuation1;
119: uniform sampler2D shadowMap1;
120: uniform mat4 shadowTransform1;
121: uniform int shadowParallel2;
122: uniform float shadowNearZ2;
123: uniform float shadowFarZ2;
124: uniform float shadowAttenuation2;
125: uniform sampler2D shadowMap2;
126: uniform mat4 shadowTransform2;
127: uniform int shadowParallel3;
128: uniform float shadowNearZ3;
129: uniform float shadowFarZ3;
130: uniform float shadowAttenuation3;
131: uniform sampler2D shadowMap3;
132: uniform mat4 shadowTransform3;
133:
134:
135: // Texture maps
136: //VTK::TMap::Dec
137:
138: // Texture coordinates
139: //VTK::TCoord::Dec
140:
141: // picking support
142: //VTK::Picking::Dec
143:
144: // Depth Peeling Support
145: //VTK::DepthPeeling::Dec
146:
147: // clipping plane vars
148: //VTK::Clip::Dec
149:
150: // the output of this shader
151: out vec4 fragOutput0;
152:
153:
154: // Apple Bug
155: //VTK::PrimID::Dec
156:
157: // handle coincident offsets
158: uniform float cCValue;
159: uniform float cSValue;
160: uniform float cDValue;
161:
162: // Value raster
163: //VTK::ValuePass::Dec
164:
165: void main()
166: {
167: // VC position of this fragment. This should not branch/return/discard.
168: //VTK::PositionVC::Impl
169:
170: // Place any calls that require uniform flow (e.g. dFdx) here.
171: //VTK::UniformFlow::Impl
172:
173: // Set gl_FragDepth here (gl_FragCoord.z by default)
174: float Zdc = gl_FragCoord.z*2.0 - 1.0;
175: float Z2 = -1.0*cDValue/(Zdc + cCValue) + cSValue;
176: float Zdc2 = -1.0*cCValue - cDValue/Z2;
177: gl_FragDepth = Zdc2*0.5 + 0.5;
178:
179:
180: // Early depth peeling abort:
181: //VTK::DepthPeeling::PreColor
182:
183: // Apple Bug
184: //VTK::PrimID::Impl
185:
186: //VTK::Clip::Impl
187:
188: //VTK::ValuePass::Impl
189:
190: vec3 ambientColor = ambientIntensity * ambientColorUniform;
191: vec3 diffuseColor = diffuseIntensity * diffuseColorUniform;
192: float opacity = opacityUniform;
193:
194:
195: // Generate the normal if we are not passed in one
196: //VTK::Normal::Impl
197:
198: vec2 factor0 = vec2(1.0);
199: vec2 factor1 = calcShadow(vertexVC, shadowMap0, shadowTransform0, shadowAttenuation0, shadowParallel0, shadowNearZ0, shadowFarZ0);
200: vec2 factor2 = calcShadow(vertexVC, shadowMap1, shadowTransform1, shadowAttenuation1, shadowParallel1, shadowNearZ1, shadowFarZ1);
201: vec2 factor3 = calcShadow(vertexVC, shadowMap2, shadowTransform2, shadowAttenuation2, shadowParallel2, shadowNearZ2, shadowFarZ2);
202: vec2 factor4 = calcShadow(vertexVC, shadowMap3, shadowTransform3, shadowAttenuation3, shadowParallel3, shadowNearZ3, shadowFarZ3);
203: fragOutput0 = vec4(ambientColor + diffuseColor, opacity);
204: //VTK::Light::Impl
205:
206:
207:
208: //VTK::TCoord::Impl
209:
210: if (fragOutput0.a <= 0.0)
211: {
212: discard;
213: }
214:
215: //VTK::DepthPeeling::Impl
216:
217: //VTK::Picking::Impl
218:
219: // handle coincident offsets
220: //VTK::Coincident::Impl
221: }
ERROR:root:1: #version 150
2021-03-11 19:57:38.991 ( 0.705s) [ 84DF2C] vtkShaderProgram.cxx:453 ERR| vtkShaderProgram (0x7fee29ba49b0): ERROR: 0:199: Use of undeclared identifier 'vertexVC'
ERROR: 0:200: Use of undeclared identifier 'vertexVC'
ERROR: 0:201: Use of undeclared identifier 'vertexVC'
ERROR: 0:202: Use of undeclared identifier 'vertexVC'
ERROR:root:ERROR: 0:199: Use of undeclared identifier 'vertexVC'
2021-03-11 19:57:39.023 ( 0.737s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b5f90): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.023 ( 0.737s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b6840): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.023 ( 0.737s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b7120): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.023 ( 0.737s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b7a00): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.023 ( 0.737s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b82e0): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.024 ( 0.738s) [ 84DF2C] vtkShaderProgram.cxx:437 ERR| vtkShaderProgram (0x7fee29ba49b0): 1: #version 150
2: #ifndef GL_ES
3: #define highp
4: #define mediump
5: #define lowp
6: #endif // GL_ES
7: #define attribute in
8: #define varying out
9:
10:
11: /*=========================================================================
12:
13: Program: Visualization Toolkit
14: Module: vtkPolyDataVS.glsl
15:
16: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
17: All rights reserved.
18: See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
19:
20: This software is distributed WITHOUT ANY WARRANTY; without even
21: the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
22: PURPOSE. See the above copyright notice for more information.
23:
24: =========================================================================*/
25:
26: in vec4 vertexMC;
27:
28:
29:
30: // frag position in VC
31: //VTK::PositionVC::Dec
32:
33: // optional normal declaration
34: //VTK::Normal::Dec
35:
36: // extra lighting parameters
37: //VTK::Light::Dec
38:
39: // Texture coordinates
40: //VTK::TCoord::Dec
41:
42: // material property values
43: //VTK::Color::Dec
44:
45: // clipping plane vars
46: //VTK::Clip::Dec
47:
48: // camera and actor matrix values
49: uniform mat4 MCDCMatrix;
50:
51: // Apple Bug
52: //VTK::PrimID::Dec
53:
54: // Value raster
55: //VTK::ValuePass::Dec
56:
57: // picking support
58: //VTK::Picking::Dec
59:
60: void main()
61: {
62: //VTK::Color::Impl
63:
64: //VTK::Normal::Impl
65:
66: //VTK::TCoord::Impl
67:
68: //VTK::Clip::Impl
69:
70: //VTK::PrimID::Impl
71:
72: gl_Position = MCDCMatrix * vertexMC;
73:
74:
75: //VTK::ValuePass::Impl
76:
77: //VTK::Light::Impl
78:
79: //VTK::Picking::Impl
80: }
ERROR:root:1: #version 150
2021-03-11 19:57:39.025 ( 0.739s) [ 84DF2C] vtkShaderProgram.cxx:438 ERR| vtkShaderProgram (0x7fee29ba49b0):
WARNING:root:ERROR: In /Users/tjcorona/Development/vtk/source/Rendering/OpenGL2/vtkShaderProgram.cxx, line 438
vtkShaderProgram (0x7fee29ba49b0):
2021-03-11 19:57:39.292 ( 1.006s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b5f90): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.292 ( 1.006s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b6840): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.292 ( 1.006s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b7120): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.292 ( 1.006s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b7a00): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.292 ( 1.006s) [ 84DF2C] vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b82e0): not a spotlight.
ERROR:root:not a spotlight.
2021-03-11 19:57:39.293 ( 1.007s) [ 84DF2C] vtkShaderProgram.cxx:437 ERR| vtkShaderProgram (0x7fee29ba49b0): 1: #version 150
2: #ifndef GL_ES
3: #define highp
4: #define mediump
5: #define lowp
6: #endif // GL_ES
7: #define attribute in
8: #define varying out
9:
10:
11: /*=========================================================================
12:
13: Program: Visualization Toolkit
14: Module: vtkPolyDataVS.glsl
15:
16: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
17: All rights reserved.
18: See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
19:
20: This software is distributed WITHOUT ANY WARRANTY; without even
21: the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
22: PURPOSE. See the above copyright notice for more information.
23:
24: =========================================================================*/
25:
26: in vec4 vertexMC;
27:
28:
29:
30: // frag position in VC
31: //VTK::PositionVC::Dec
32:
33: // optional normal declaration
34: //VTK::Normal::Dec
35:
36: // extra lighting parameters
37: //VTK::Light::Dec
38:
39: // Texture coordinates
40: //VTK::TCoord::Dec
41:
42: // material property values
43: //VTK::Color::Dec
44:
45: // clipping plane vars
46: //VTK::Clip::Dec
47:
48: // camera and actor matrix values
49: uniform mat4 MCDCMatrix;
50:
51: // Apple Bug
52: //VTK::PrimID::Dec
53:
54: // Value raster
55: //VTK::ValuePass::Dec
56:
57: // picking support
58: //VTK::Picking::Dec
59:
60: void main()
61: {
62: //VTK::Color::Impl
63:
64: //VTK::Normal::Impl
65:
66: //VTK::TCoord::Impl
67:
68: //VTK::Clip::Impl
69:
70: //VTK::PrimID::Impl
71:
72: gl_Position = MCDCMatrix * vertexMC;
73:
74:
75: //VTK::ValuePass::Impl
76:
77: //VTK::Light::Impl
78:
79: //VTK::Picking::Impl
80: }
ERROR:root:1: #version 150
2021-03-11 19:57:39.294 ( 1.008s) [ 84DF2C] vtkShaderProgram.cxx:438 ERR| vtkShaderProgram (0x7fee29ba49b0):
WARNING:root:ERROR: In /Users/tjcorona/Development/vtk/source/Rendering/OpenGL2/vtkShaderProgram.cxx, line 438
vtkShaderProgram (0x7fee29ba49b0):

Answer 1

Shadowing is currently not implemented in PyVista, and I don't know how reliable it is in vtk (or how to make it work reliably).
Quoting from this comment:
As for the shadows, it works 100% of the time 60% of the time. We should add as an option and then users can play around with it. I'm sure at some point real time ray tracing is going to be a hardware feature even down to integrated GPUs, so it's a matter of time until this becomes a well tested/supported feature.
For instance on my laptop with an integrated GPU shadow rendering is a mess.
With window size (1000, 1000):
With window size (2000, 1000):
In any case I can more or less reproduce the errors you're seeing. The first error comes partly from PyVista:
vtkLightActor.cxx:285 ERR| vtkLightActor (0x7fee299b5f90): not a spotlight.
ERROR:root:not a spotlight.
This is because PyVista Light objects have a vtkLightActor attached to them, but these should be hidden (i.e. never rendered) unless the light is a spotlight (the only case where a vtkLightActor makes sense). As I noted on the aforementioned issue the error shouldn't arise and it makes little sense that shadowing affects this. If this ended up staying a problem we could try mitigating it in PyVista, but it would be a lot of complexity for questionable gain.
The second error from the shader is very much VTK and I don't know what exactly it's about. Considering how this is not a supported feature of PyVista and you're using vtk directly, it probably makes more sense to raise the issue with vtk. (Although I don't know if there might be something we could put in on the PyVista side to make it work more reliably.)
For what it's worth you might be able to swap your if shadows block with just this:
plotter.renderer.SetUseShadows(shadows)
At least I see the same behaviour if I use that. So in cases where your code works for you, it might be a simpler alternative.